The Clachan Bridge is a simple, single-arched, hump-backed masonry bridge spanning the Clachan Sound, 13 kilometres southwest of Oban in Argyll, Scotland. The bridge links the west coast of the Scottish mainland with the island of Seil. Originally designed by Thomas Telford, and built between 1792 and 1793 by engineer Robert Mylne, the bridge became known as 'The Bridge over the Atlantic'. It was designed with a high arch, of roughly 22 metres span and about 12 metres above the bed of the channel, to allow the passage of vessels of up to 40 tonnes at high tide. The bridge is still in use today, forming part of the B844 road, and is in the care of Historic Scotland.